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May 06, 2014
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DESERT BLOOM: Emerald Ash Borer

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Angela

There are so many trees out in the world, but only a relatively small number can survive, much less actually flourish, in our challenging environment. We do insist on growing some poorly fitting ones: looking around the valley, there are lots of marginal purple leaf plums, short-lived chitalpas, and even the occasional weeping willow. When I see those, I get a little incensed, since there’s no excuse for growing them in the middle of the Mojave – they only belong in places that get considerably more than four and a quarter inches of rainfall per year!

MesquiteOf course, true desert trees, like mesquite and desert willow (which is not even remotely related to the weeping one), grow and thrive here.  Even here, though, we do have a bigger selection that just those two. Included in that group are several of the ashes. You can find various kinds of ash trees growing perfectly well all around the country. I recently read that there are over seven billion ash trees growing in the US!

Arizona AshGiven the name, Arizona ash would be an obvious choice for this region, but they’re not alone. Raywood, fan-tex, velvet ash – they all tolerate desert conditions remarkably well, as long as they receive enough water and the occasional hit of compost tea. We have so few great tough shade trees in the desert; we need to keep them healthy and happy.

Not everything is so great for ash trees in this country, unfortunately. There is a pest making its way across the continent, causing devastation in its path. The only good thing about it is that it only affects ash.

This pest is a slender little insect, about ¼ to ½ inch long, colored a vivid green, that destroys ash trees. The emerald ash borer has been marching from east to west, killing its hosts.

Such a small thing, with such a pretty color, and such a terrible villain! From the time it was introduced into the US (not deliberately introduced, obviously), it has killed tens of millions of ash trees. Apparently, it arrived from Asia on packing crates in cargo ships and planes. Since its first sighting in 2002, it spread throughout the northeast and a sizeable chunk of the central United States.

To try and keep it from spreading even more than it already has, certain agencies, including the Department of Agriculture, have imposed quarantines on wood from 21 states and two Canadian provinces. This is one of the few ways to slow down its migration.

Still, it continues to spread, albeit more slowly than it would otherwise.

The difficulty is that people don’t always pay attention. I’m not sure who drew it, but there’s a cartoon that gives a good explanation of how this insect’s been able to continue its lethal journey. In this cartoon, a big man is carrying a bundle of firewood. Strolling next to him is an emerald ash borer wearing a t-shirt that says, “I’m with stupid”.

Ash borer

People who want to save a few dollars frequently carry their own firewood when they go camping. Too often, they’re bringing it from infested states where there’s now lots of dead ash wood, to places where the borer hasn’t yet been established.  

Happily, this bit of misery isn’t in Nevada – yet. Since we need to keep our ash trees alive, all of us should be careful and observant. 

As I said, it’s only up to a half inch long, so the insect itself’d be easy to miss.

It’s not the adult that causes the plant to die, however. Adults eat a few leaves, but don’t kill the tree. Its voracious babies, on the other hand, are the bad guys. If an ash has a D shaped hole in the bark, look closer. A D-shaped hole is the exit for the adults who grew from the juveniles who destroyed part of the tree’s circulatory system.

This is a real concern. If you see this kind of a hole, especially if the ash tree looks stressed, call Cooperative Extension: (702) 222-3130

For KNPR’s Desert Bloom, this is Dr. Angela O’Callaghan of the University of Nevada Cooperative Extension.

See discussion rules.

Archives

AngelaJul 14, 2014 | Protect Fruit Trees from Birds
If you put a good deal of care into growing fruit trees, there are likely some birds who will take advantage of your effort. Here's Angela O'Callaghan.

NormJul 10, 2014 | Palm Care, Part 2
To keep, or not to keep. Norm Schilling ponders his palm trees, on this edition of Desert Bloom.

NormJun 10, 2014 | Palm Care
Norm Schilling has mixed feelings about how we use Palms in our yards. Full grown palm trees transplanted into the entry way of a mall is a common sight that tells Southern Nevadan's "something" is nearly open for business. He reminds us that those palms come with challenges.

AngelaJun 3, 2014 | Hot Weather Plants
As temperatures across the Valley begin to climb, you might be wondering what will survive in your garden in the months ahead and what probably won't. There are some 'sweet' options. Here's Angela O'Callaghan

NormMay 20, 2014 | Desert Color
Norm Schilling just got back from Belize and has some ideas for lush leaves in your desert yard. He reflects on some well suited plants to provide color and variety in this edition of Desert Bloom.

AngelaMay 6, 2014 | Emerald Ash Borer
Raising a healthy shade tree in the Mojave is not always easy. And if one particular insect makes its way here, it could get even harder. Here's Angela O'Callaghan with Desert Bloom.

NormApr 22, 2014 | The Right Plants
Our current warm spell gives the impression that some plants can thrive when they aren't really suited to our desert. Norm Schilling has some examples.

NormMar 24, 2014 | Spring Garden Party
Spring is here and the garden is blooming . . . so invite some friends to enjoy the rewards of gardening!

AngelaMar 10, 2014 | Lady Banks
If you love roses, but don't care for thorns, you may want to call on 'Lady Banks.' Here's Angela O'Callaghan with Desert Bloom.

NormFeb 26, 2014 | Signs of Spring
It may be February, but if you are paying attention, signs of Spring are visible. Dwarf peach and Mexican plum trees are in bloom. Vibrant Red Spraxis can be seen among the falling Almond blossom. Watch gardening expert Norm Schilling transplant an offshoot. Check out the slide show of photos taken from his backyard.

AngelaFeb 18, 2014 | Mulch is for Winter
Rewards for using mulch in your landscape can be had year-round. Mulch is about mulch more than just "good looks" according to Angela O' Callaghan. In any climate, and certainly in a desert, mulch is an ecologically sound way to conserve our limited soil moisture and to control weeds.

NormFeb 4, 2014 | Investing for Spring
Temperatures are scheduled to stay cool this week, but Norm Schilling finds his yard is ready for Spring. He reflects on techniques to keep older trees healthy even as the surrounding yard may change. Bigger, older trees may need more water.

AngelaJan 13, 2014 | Freezing Temps
If your garden looks like it's been zapped by Jack Frost, there's still a chance that all is not lost. Delicate desert plants can suffer chill damage even when the temperature stays above freezing. Well-established plants should survive.

NormDec 31, 2013 | Leave the Leaves
Just because most of the leaves have fallen from the trees, it doesn't mean you have to rake them all up. Norm Schilling says it's better to use the leaves as mulch to protect the plants and make rich soil. Some woody plants can be pruned now, while others should wait another month or two.

AngelaDec 13, 2013 | Winter Greens
It is the season to enjoy some winter gardening. In Southern Nevada, a cold-snap does not have to mean that your garden is done for. Angela O'Callaghan gives a few cold facts.

NormDec 3, 2013 | Winter Watering
After a recent rain followed by a cold snap this week, Norm Schilling digs in to figure out how much water is needed this time of year. Touch the leaves to get a feel and don't water much at all for the next few months.

AngelaNov 18, 2013 | Herb Gardens
Our desert environment may be hard to handle for many plants, but it is possible to grow your own herbal remedy. The healing properties of some herbs are still widely recognized. Even though we rarely have to rely on them to deal with our infirmities, Angela O'Callaghan says many herbs are pretty and simple to grow.

NormNov 5, 2013 | Fall Color
Our second Spring is in full bloom. Norm Schilling shares his favorite plants that are bringing color to the yard right now, including Chocolate Flower, Mexican Bush Sage, Autumn Sage and ornamental grasses.

AngelaOct 29, 2013 | Pumpkins
Halloween just wouldn't be the same without the jack-o-lantern. But there's more to the tradition of decorating squash than meets the eye. Angela O'Callaghan says pumpkins are more than decorations for a single day. They're food, and a very good food at that.

NormSep 30, 2013 | Fall Pruning and Mulching
Pruning for aesthetics and mulching for rich soil quality are on his to-do list before he gets started in earnest on fall planting. Find out where to find mulch and mulch more on this week's edition of Desert Bloom.

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